Patzke, Justus
[Author];
Hesse, Roland
[Author];
Witt, Markus
[Author];
Nehlsen, Edgar
[Author];
Fröhle, Peter
[Author]
;
Technische Universität Hamburg,
Technische Universität Hamburg Institut für Wasserbau
Measurement and comparison of settling velocities of cohesive sediments from the German estuaries Weser and Ems
Footnote:
Sonstige Körperschaft: Technische Universität Hamburg
Sonstige Körperschaft: Technische Universität Hamburg, Institut für Wasserbau
Description:
Settling and sedimentation of fine-grained sediments is a physical phenomenon influenced by bio-geochemical processes that occurs in natural water bodies such as rivers, channels and estuaries. Of particular concern are estuaries maintained for navigation. The deepening of waterways to improve the navigability for ever larger container ships has the potential to intensify sedimentation and the accumulation of cohesive sediments, particularly within the estuarine turbidity maximum (ETM). For example, significant net sedimentation and accumulation are observed in the ETM of the Weser estuary even in the centre of the navigational channel, where high flow velocities favour sediment transport and erosion. Dredging is the main method of maintaining a channel, which requires large financial investment and also has potential negative environmental impacts. In engineering practice, numerical modelling of the ETM and accumulation zones is an important tool to improve channel maintenance. Knowledge of site-specific information on settling velocities is therefore essential, as underlying processes cannot be simulated universally valid yet and require sufficient local parametrisation.
The research project FAUST (For An improved Understanding of estuarine Sediment Transport) addressed the challenge of net sedimentation and accumulation in the navigational channel by investigating the transport properties of cohesive sediments (mainly from the Weser estuary) in field and in laboratory studies. The conceptual design of the project FAUST has been presented in Patzke et al. (2019). Research on sediment erodibility, sediment fractions and density profiles has been published recently (Patzke et al. 2021; Patzke et al. 2022). The follow-up project ELMOD (Simulation and analysis of the hydrological and morphological development of the Tidal Elbe for the period from 2013 to 2018) focuses on sediment transport processes in the Elbe estuary. The findings and derived model parameterisations of the projects contribute to the development of large-scale 3D morphodynamical-numerical models. In this submission, laboratory-derived effective settling velocities of natural cohesive sediments from two German estuaries are examined.